Protective layers for sputter coated article

ABSTRACT

Tin is added to a zinc cathode target to enhance the sputter efficiency of the target. Films deposited using the cathode, e.g., greater than zero but less than 10 weight percent tin and greater than 90 but less than 100 weight percent zinc improve the chemical durability of a high transmittance, low emissivity coating stack over coating stacks having zinc oxides without tin oxide. High transmittance, low emissivity coating stacks are heated with the heated coating having reduced haze by selecting the thickness of metal primer layer between an infrared reflective film, e.g. a silver film and a dielectric film, e.g., a 52-48 zinc stannate, zinc oxide, tin oxide film or a zinc oxide film. Also disclosed are enhancing films that lower the resistivity of silver films deposited thereon and improve chemical durability of the coating stack.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part application of applicationSer. No. 09/302,409, filed Apr. 30, 1999. This application claimspriority to U.S. Provisional Application Ser. No. 60/085,129, filed May12, 1998.

FIELD OF THE INVENTION

This invention relates, in general, to protective layers for sputtercoated articles such as coated or uncoated glass or transparent. Sucharticles with the protective layers are shippable, heat treatable, canhave low emissivity coating or coatings. The invention also relates tothe coated articles and to methods of making the coated articles.

DISCUSSION OF THE PRESENTLY AVAILABLE TECHNOLOGY

U.S. Pat. No. 4,610,771 (“U.S. Pat. No. '771”) discloses anantireflective sputtered metal oxide film deposited using a zinc/tinalloy target. U.S. Pat. No. '771 in column 3, line 26, to column 4, line12, discusses the use of the alloy target to deposit a zinc stannatefilm having, in general, oxides of zinc and tin preferably inproportions of 10 to 90 percent zinc and 90 to 10 percent tin.

Although the zinc/tin alloy target disclosed in U.S. Pat. No. '771 todeposit the zinc stannate film is acceptable, there are limitations.More particularly, in a low E coating such as the type described in U.S.Pat. No. '771, an infrared reflecting metal film or layer, e.g., silveris deposited on the zinc stannate film. A silver film deposited on asputtered zinc stannate film has a higher electrical resistivity andhigher emissivity than a silver film deposited on a sputtered zinc oxidefilm or layer. More particularly, U.S. Pat. No. 5,821,001 (“U.S. Pat.No. '001”) discloses a silver film deposited on a zinc oxide film; theatoms of the silver film deposit in a form characterized by a lowelectrical resistivity which provides the silver film with a lowemissivity. In depositing the zinc oxide film the process parameters areselected to deposit a zinc oxide layer with a suitable crystallinity orpreferential crystal growth for favorably affecting deposition of thesilver atoms of the silver film.

Sputtering zinc in a reactive atmosphere, e.g., oxygen, to provide azinc oxide film over which a silver film having a low electricalresistivity is deposited has drawbacks. For example, it is difficult toreactively sputter a pure zinc target, i.e., a target of about 100% zincmetal, in a reactive atmosphere such as oxygen for reasons discussed inmore detail below.

U.S. Pat. No. '001 also discloses a heat treatable low emissivity film.The thickness of the primer layers, e.g., titanium films, may beincreased to provide enhanced mechanical durability, i.e., improve shearresistance. The shear resistance test consists of applying 20 successivestrokes of a cloth wetted with deionized water against the coatedsurface of glass, followed by visual examination of the tested area.Depending on the appearance of the tested area, letter grades of D−, D,D+ . . . A, A+ are assigned to the coating; then, for numericalanalysis, assignments of 5 to D−, 10 to D, 55 to A, and 60 to A+ aremade. If a coating shows no signs of shear, not even barely visiblescratches, then it receives a maximum rating of 60. Coatings thatdisplay uniform shear and delamination at any interface of themulti-layer coating within the test area receive a failing rating ofzero. Other levels of performance receive intermediate scores. Thismethod of coating durability characterization has been found tocorrelate well with field performance of the coating. The drawback withusing thick primer layers is that the coating stack after heating, e.g.,glass tempering or glass bending operations, is likely to have a hazyappearance when viewed using a dark room, flood-light haze test. In thedark room, floodlight haze test, the coated specimen is viewed inreflection in a dark room at various viewing angles relative to aspotlight, in order to find the geometry yielding maximum scattering oflight, or, in other words, haze, possible from the coating. If there isno geometry that can make haze observable, an A+ rating is assigned tothe sample. Very poor samples receive D−. For purposes of numericalanalysis, the letter grades are given values of 5 to 60, as describedabove for the shear test. Lower haze corresponds to higher numericalvalues.

As can be appreciated by those skilled in the art of making sputteredcoatings, it would be advantageous to provide a zinc target that may besputtered in a reactive atmosphere without the drawbacks of thepresently available zinc targets and to provide low emissivity coatedarticles that have mechanical durability so that the coated article maybe shipped and subsequently heated without the heated coating havinghaze.

The disclosures of U.S. Pat. Nos. '771 and '001 are hereby incorporatedin toto by reference.

SUMMARY OF THE INVENTION

This invention relates to a sputter cathode target having tin preferablyin an amount greater than zero and less than 10 weight percent of thetotal weight of the target material, and zinc in an amount preferablyless than 100 weight percent and more than 90 weight percent of thetotal weight of the target material. Hereafter, unless indicatedotherwise, the term “weight percent” means the weight percent of thetotal weight of the target material.

As used herein, “a zinc stannate film,” e.g., of the type discussed inU.S. Pat. No. '771 is an oxide of an alloy of zinc and tin. The cathodeused is made of an alloy of zinc and tin. A “zinc oxide, tin oxidefilm,” is a film having oxides of tin and zinc. The cathode used tosputter the zinc oxide, tin oxide film is made of zinc having additionsof tin as is discussed in detail below.

In one embodiment of the invention a coating stack has a zinc stannatefilm deposited on a glass substrate, a zinc oxide, tin oxide filmdeposited on the zinc stannate film; an infrared reflecting film, e.g.,silver, deposited on the zinc oxide, tin oxide film; a primer layer,e.g., a titanium metal film, deposited on the infrared reflecting film;a zinc oxide, tin oxide film deposited on the primer film, a zincstannate film deposited on the zinc oxide, tin oxide film; an infraredreflecting film deposited on the zinc stannate film; a primer layerdeposited on the infrared reflecting layer; a zinc oxide, tin oxide filmdeposited on the primer layer, a zinc stannate film deposited on thezinc oxide, tin oxide film; and a protective layer, e.g., a titaniummetal film and/or a titanium oxide film in either order, deposited overthe zinc stannate film. In another embodiment of the invention, a zincoxide film is used in place of the zinc oxide, tin oxide film. In afurther embodiment of the invention, a zinc stannate film is used inplace of the zinc oxide, tin oxide film. When a zinc stannate film isused in place of the zinc oxide, tin oxide film, the zinc stannate filmsdiffer in composition by at least 5 weight percent. For example, whenone of the zinc stannate films is about 50 weight percent zinc and 50weight percent tin, the other zinc stannate film is about 10-45 or 55-90weight percent zinc and 55-90 or 45-10 weight percent tin. In a stillfurther embodiment of the invention, a first deposited zinc stannatefilm is 50±10 weight percent zinc and 50±10 weight percent tin. Thesecond deposited or overlying zinc stannate film has tin equal to orgreater than 10 weight percent and less than 40 weight percent andpreferably 20 weight percent, and has zinc equal to or less than 90weight percent and greater than 60 weight percent and preferably 80weight percent. Overlying zinc stannate films having 90 weight percentzinc and 10 weight percent tin have been used.

Another aspect of the present invention is the composition or films ofthe protective layer. Of course, the protective layer can be for anymulti-layered stack with one or more antireflective layers on asubstrate. This multi-layered stack has at least one layer of at leastone infrared reflecting film which can be preceded on the near sidetowards the substrate by one or more dielectric and/or zinc- and/ortin-containing films and can be followed on the side away from thesubstrate by one or more layers of one or more dielectric and/or zinc-and/or tin-containing films and/or a primer layer. This is also the typeof multi-layered stack for the protective layer. Any zinc- and/ortin-containing films can be zinc oxides or tin oxides or the zincstannates like those in Patents '771 and '001. The protective layer iseither a metal film or silicon film or metal oxy-material film orsilicon oxy-material film or both. The metal oxy-material or siliconoxy-material film is either or both metal oxide or silicon oxides filmsor metal oxynitride or silicon oxynitride films. These metal, metaloxide and metal oxynitride films have one or more metals that are thesame or different from metal film to metal oxide or oxynitride filmwhere the metals are those transition metals of Groups, 4, 5, and 10 ofthe Periodic Table of Elements for the Revised Chemical Element GroupNotation having upto 18 groups and alloys thereof that are capable ofbeing sputtered coated. For the protective layer the order can be metalfilm and metal oxide or oxynitride film or the reverse. The protectivelayer can be the outermost layer on the multi-layered stack but it onlyneeds to be in a position in the multi-layered stack where it canperform the protective function for providing some chemical and/ormechanical durability to the multi-layered stack. Hence there can beadditional film or coating layers over the protective layer if desired.

The above-described coating stack has mechanical and chemicaldurability. The coatings of the instant invention in addition to havingmechanical and chemical durability which make them acceptable forshipment can be heat treated with the heat treated coating havingreduced haze. The reduction in haze after heating is accomplished byselecting metal primer thicknesses which is discussed below. Theprocedure for determining haze was discussed above. As used herein areduction in haze is a numerical increase of about 10. An advantage ofthe coatings of the instant invention is that a coating of the inventionmay be deposited on a substrate, the coated substrate shipped to afabricating facility where the coated substrate is heat-treated, e.g.,heated to temperatures up to about 1350° F. (732° C.). The coating ofthe invention has particular application in the making of solar controlautomotive windshields. Sheets of glass having a low emissivity coatingof the invention are coated in one facility and then shipped to anotherfacility where the coated glass sheet is processed, e.g., into anautomobile windshield.

DISCUSSION OF THE INVENTION

For a full appreciation of the various embodiments of the invention, theembodiments will be discussed separately and then combined. The firstembodiment of the invention to be discussed is the use of a zinc cathodehaving low amounts of tin to improve the deposition of zinc oxide filmsand the benefits of a zinc oxide film having low amounts of tin.

The embodiments of the invention relating to zinc sputtering targethaving low amounts of tin and to a method of reactively sputtering suchzinc targets to sputter deposit a zinc oxide, tin oxide film will bediscussed. As will be appreciated, the invention contemplates using thetarget of the instant invention to deposit a zinc oxide, tin oxide filmover or under an infrared reflective film, e.g., gold, silver oraluminum film, other metal films, e.g., primer films such as a titaniummetal, or ceramic films, or other dielectric films.

The sputtering cathode target in one embodiment of the invention hasgreater than zero weight percent and less than 10 weight percent tin,and less than 100 weight percent and more than 90 weight percent zinc toimprove the emissivity of an infrared reflective film, e.g., a silverfilm, deposited on the zinc oxide, tin oxide film and to improve thesputtering of the zinc cathode target having low amounts of tin. Thecathode target of the instant invention may also be defined as havinggreater than 0 and less than 10 weight percent tin with the majority ofthe balance zinc, or as having less than 100 weight percent and morethan 90 weight percent zinc with the majority of the balance tin. Beforediscussing this embodiment of the invention, the drawbacks and/orlimitations of reactively sputtering a zinc cathode target without tinand limitations of zinc oxide films deposited using such cathodes arediscussed for a better appreciation of the invention.

Typically, a metal target is reactively sputtered in a gas such asoxygen, or gas mixture of oxygen with other gases such as nitrogen,argon or helium. Sputtering in a gas mixture will result in a highersputtering rate for a stable process but requires more control tomaintain the process stability, e.g., requires controlling flow rate oftwo gases. Because of the higher sputtering rate, it is preferred tosputter in a gas mixture rather than in oxygen alone. In either case theresulting coating is a metal oxide, e.g., zinc oxide when a zinc targetis used.

Zinc oxide is a common dielectric material that is used as a highrefractive index film in coating stacks having low emissivity. In theflat glass industry these coatings are usually applied by horizontalvacuum coaters using high power supplied from a direct current source toenergize cathodes that sputter layers onto glass substrates. Highercoater throughput requires higher power density to the cathode target.This in turn increases the tendency for the targets to arc, particularlyduring reactive sputtering.

During reactive sputtering the frequency of arcing of the zinc cathodetarget increases with time, and debris in the form of powder and flakesbuilds up on the target surface and adjacent areas. Debris in the formof powders, flakes and splatter eventually falls onto the surface of thesubstrate being coated resulting in unacceptable coated product. Furtherthe arcing increases to a point where the process becomes unstable. Inaddition, areas of the target surface have a tendency to blacken overtime. These blackened areas are nonconductive, thus limiting thesputtering rate and leading to non-uniformity in the coating.

The arcing and debris buildup to some degree may be reduced by periodicsputter cleaning as is known by those skilled in the art of sputtercoating. One technique for sputter cleaning is to periodically sputterthe targets for a certain time period in an inert gas, such as argon orhelium, which sputters the target as a metal. Sputter cleaning to somedegree removes the oxide buildup on the target surface that causesarcing. The black areas on the target may not be reduced by sputtercleaning. The debris and arcing, however, continually degrade thetarget, and after a period of time, the coater downtime increases and,consequently, there is less production time for the coater. Zinc targetsbecause of their tendency to frequently arc during sputtering aredifficult to sputter clean and require longer and more frequentcleaning.

In the practice of the invention, tin is added to a zinc target toreduce if not eliminate the above drawbacks, e.g., reduce the amount offlaking debris, reduce powdery buildup on the target, minimize arcing,and minimize, if not eliminate, blackening of the target surface areas.The amount of debris and degrading of the zinc target of the instantinvention is considerably less with time than for a pure zinc target. Asa result, less periodic target cleaning is required with less durationof the cleaning in an inert gas.

As previously discussed, U.S. Pat. No. '771 discloses a zinc-tin alloytarget to deposit a zinc stannate film, i.e., an oxide of a zinc tinalloy having 10 to 90 weight percent zinc and 90-10 weight percent tin.The zinc-tin alloy cathode target of U.S. Pat. No. '771 provides a zincstannate film that has better chemical durability than a zinc oxidefilm. Further, the zinc-tin alloy cathode target has less arcing andminimal debris buildup, e.g., there is no measurable powder buildup. Asis well-known in the art of sputter coating, zinc oxide films readilydissolve in acid and base solutions; zinc stannate films have reducedsolubility in acid or base.

Although the properties of the zinc oxide, tin oxide film of the instantinvention have not been studied in great detail, it is believed that thefollowing will occur. As the tin approaches zero weight percent, thechemical durability of the deposited film decreases, and the problemsassociated with sputtering a zinc target in a reactive atmosphereincrease. As the weight percent of tin approaches ten, the chemicaldurability of the zinc oxide film increases, and the problems associatedwith sputtering a zinc target in a reactive atmosphere decrease. Theelectrical resistivity of a silver film deposited on the zinc oxide, tinoxide film is expected to be similar to a silver film deposited on azinc oxide film. In the practice of this embodiment of the invention, azinc target having tin greater than zero and less than ten weightpercent is a useable range; 0.5 to 9.5 weight percent of tin is apractical range; 4 to 8.5 weight percent of tin is a preferred range,and 5 to 9.5 weight percent of tin is a more preferred range. The weightpercent of tin and zinc in a zinc oxide, tin oxide film is expected tobe similar to the weight percent of zinc and tin in the target.

As can now be appreciated, as the weight percent of tin in the zinccathode increases, the chemical durability of the deposited film isexpected to increase. Further, the crystalline structure of the zincoxide film having tin in weight percents greater than zero and less thanten is similar if not identical to the crystalline structure of zincoxide film having zero weight percent of tin. Further, a zinc stannatefilm having 60-90 weight percent zinc and 10-40 weight percent tin havesimilar crystalline structures as zinc oxide. Therefore, it is expectedthat emissivity of silver film deposited on a zinc oxide film will besimilar to a silver film deposited on a zinc stannate film having 60-90weight percent zinc and 10-40 weight percent tin. At values of less than60 weight percent zinc, the crystalline structure starts to change andthe emissivity and resistivity start to increase. Transmission ElectronMicroscopy has shown a weak zinc oxide electron diffraction pattern fora zinc stannate film having 66 weight percent zinc and 34 weight percenttin, and an amorphous structure for zinc stannate film having 47 weightpercent zinc and 53 weight percent tin.

The coated articles disclosed in U.S. Pat. No. '001 and U.S. patentapplication Ser. No. 09/023,746 filed Feb. 13, 1998, in the names ofMehran Arbab, Russell C. Criss, Gary J. Marietti and Paul A. Medwick for“Coated Articles” (hereinafter “U.S. patent application. No.09/023,746”) may be made practicing this embodiment of the instantinvention which includes but is not limited to sputtering a cathodetarget having 92 weight percent zinc and 8 weight percent tin in anatmosphere having more than 75% oxygen and the remainder argon. Further,problems discussed above associated with sputtering a zinc target areexpected to be minimized if not eliminated.

The discussion will now be directed to improving chemical durability ofthe coating stack, reduction of haze of the coating stack and decreasedemissivity of the infrared reflective metal, e.g., silver. “Chemicaldurability” means the coating is not readily attacked by acid or basesolutions. Reference may be had to U.S. Pat. Nos. '001 and '771 for adiscussion on chemical durability. The test for haze was discussedabove.

From the above discussion, the emissivity of the silver film may bereduced by depositing the silver layer on a zinc oxide film; a zincoxide, tin oxide film or a zinc stannate film having zinc in the rangeof 60 to 90 weight percent and tin in the range of 10 to 40 weightpercent. Further, from the above discussion, chemical durability of alayer having a zinc oxide film under a silver film and over a zincstannate film may be enhanced by adding tin to a zinc target to providea zinc oxide, tin oxide film, or a zinc stannate film. As used herein,“a chemical and electrical enhancement film” is a zinc oxide, tin oxidefilm and/or a zinc stannate film having zinc in the range of 60 to 90weight percent and tin in the range of 10 to 40 weight percent. Thechemical and electrical enhancement film of the invention may be used inplace of zinc oxide films to enhance chemical durability of the coatingstack while obtaining a silver film having low emissivity. By way ofillustration, coated articles having a glass substrate/zinc stannatefilm/zinc oxide film/silver film/titanium metal primer film/zinc oxidefilm/zinc stannate film/zinc oxide film/zinc stannate film/titaniummetal and/or titanium oxide or oxynitride protective overcoat may bechemically enhanced by using the chemical and electrical enhancementfilm of the invention for one or more or all of the zinc oxide film(s)of the above coating stack.

Another coated article includes glass substrate/zinc stannate film/zincoxide film/silver film/titanium metal primer film/zinc oxide film/zincstannate film/titanium metal and/or titanium oxide or oxynitrideprotective overcoat. As can now be appreciated, the chemical andelectrical enhancement film of the invention may be substituted for oneor more or all of the zinc oxide film(s) of the above coating.

In the practice of the instant invention, a dielectric layer may includea zinc stannate film, and a chemical and electrical enhancement film.Where the chemical and electrical enhancement film is zinc stannate, thedifference between the composition of the zinc stannate film and thezinc stannate film of the chemical and electrical enhancement film is atleast 5 weight percent zinc. For example, and not limiting to theinvention a zinc stannate film having 58 weight percent zinc and 42weight percent tin may be used with a zinc stannate film (chemical andelectrical enhancement film) having 63 to 90 weight percent zinc and 10to 37 weight percent tin.

The discussion will now be directed to the embodiment of the inventionto provide a coating stack that is chemically and mechanically durableand a coating stack that has reduced haze after subjecting the coatingstack to elevated temperatures, e.g., but not limiting to the invention,above room temperature and below about 1350° F. (732° C.). As will beappreciated by those skilled in the art, the invention is not limited tothe coatings discussed below which are presented for illustrationpurposes only. The following Table 1 provides a few embodiments ofcoating stacks that may be used in the practice of the invention;however, as will be appreciated, the invention is not limited thereto.

TABLE 1 Coating FILM Samples Substrate 1 2 3 4 5 6 7 8 9 10 11 12 13 1 XX X X X X X 2 X X X X X X X X X X 3 X X X X X X X X X X 4 X X X X X X XX X X 5 X X X X X X X X X X X 6 X X X X X X X X X X X 7 X X X X X X X XX X X 8 X X X X X X X X X X X X 9 X X X X X X X X X X X X X 10 X X X X XX X X X X X X X 11 X X X X X X X X X X X X X X 12 X X X X X X X 13 X X XX X X X X Layers A B C D E F G H

The second column from the left is entitled “Substrate.” The material ofthe substrate is not limiting to the invention and may be made of anymaterial, e.g., glass, fiberglass, plastic, metal, wood or ceramic. Thetype of articles that are made in the preferred practice of theinvention are transparencies for residential and commercial buildings,and land, air, space, above, on and below water vehicles, therefore, thesubstrate is preferably transparent and made of glass, and flexible andrigid plastics. Glass when used may be clear or tinted and made by anyprocess including the float glass manufacturing process, and the type ofglass is not limiting to the invention. It is expected that the coatedarticle will be subjected to elevated temperatures; therefore, thesubstrate selected should be able to withstand the elevatedtemperatures. In our discussion, but not limiting to the invention, thesubstrates are glass sheets or pieces.

The columns numbered 1-13 are films, and the columns labeled A-H arelayers, of coating stacks that incorporate features of the invention.The layers (see the bottom of the Table 1) include at least one film andas shown in the Table 1 up to 3 films. The layers A, D and G aredielectric layers. The index of refraction of the dielectric films ofthe Layers A, D and G is preferably greater than the index of refractionof the transparent substrate to anti-reflect the infrared reflectionlayer. The invention is not limited to the type of dielectric films thatmay be used in combination with the chemical and electrical enhancementfilm of the invention. Dielectric films that may be used in the practiceof the invention include but are not limited to zinc oxide, tin oxide,silicon oxide, silicon nitride, and silicon oxynitride. It is preferredthat films 1, 6 and 11 of the layers A, D and G, respectively are each azinc stannate film having 52 weight percent zinc and 48 weight percenttin. The films 2, 5 and 7, and 10 of the layers A, D and G respectivelymay be a zinc oxide film, or a chemical and electrical enhancement filmof the invention. Coating examples 12-13 of Table 1 are propheticexamples, but these coating examples show the presence of one or both offilms 12 and/or 13 as layer H. Coating examples 12 and 13 are those withthe least number of films which can have either or both of theprotective films for the protective layer. Of course any of the othercoating examples 2-8 can also have either or both for the H layer.

In the following discussion, the substrate is soda-lime-silicate clearglass and has an index of refraction about 1.5. As is known in the art,varying the thickness of the film and layers changes the color of thecoated article, or may provide a coating with a neutral color. It isexpected that in the practice of the invention, the dielectric layersand/or films have a thickness in the range of 600±500 Angstroms. Thethickness of the zinc oxide film or the chemical and electricalenhancement film should be sufficient to affect the crystal structure ofthe silver film to be deposited thereon.

The films 3 and 8 of layers B and E, respectively, are infraredreflecting films and may be of any material that reflects infraredenergy, e.g., but not limiting to gold, silver and aluminum. In thepractice of the invention silver is preferred. The thickness of thesilver is not limiting to the invention and is selected to provide atransparent coating having low emissivity. Silver films having athickness of 200±150 Å and preferably 100±25 Å may be used in thepractice of the invention.

The films 4 and 9 of the layers C and F, respectively, are primer filmswhich have the function of (1) protecting the infrared metal layer fromoxidizing during sputtering of the dielectric films, (2) protecting theinfrared reflecting layer during high temperature processing, (3)reducing haze formation in the coating stack during heating, and/or (4)providing the coating stack with mechanical durability for shipping thecoated article. Primer films may be any of the type known in the art,e.g., metals such as titanium or ceramic, of the type disclosed in U.S.patent application Ser. No. 09/215,560, filed Dec. 8, 1998, thedisclosure of which is hereby incorporated by reference. In the practiceof the invention, the primer layer is preferably titanium.

Films 12 and 13 of the layer H is or are protective films to provideadditional chemical and mechanical durability for the coating stackduring shipping and storage. The protective films are thin film sputtercoating of metals or silicon and metal or silicon oxy-materials wherethe metals and metal oxy-materials that may be used can be titanium,titanium dioxide, titanium oxynitride, zirconium, zirconium oxides,zirconium oxynitrides, niobium, niobium oxides, niobium oxynitrides,tantalum, tantalum oxide, tantalum oxynitride, chromium, chromic oxides,chromic oxynitrides, nickel oxide and/or oxynitrides, and silicon oxide,silicon dioxide, silicon aluminum nitride and alloys, combinations ormixtures of any two or more of these including those like nickelchromium, silicon chromium, silicon chromium nickel, and silicon nickel.Also the aforementioned oxides can be oxynitrides. The aforementionedmetals are useful as single films for the protective layer at numerouslocations in a stack of layers when the stack of films is heat treatedand the metals are converted by the heat to metal oxide films or metaloxynitride films. The temperature of heating are those usuallyencountered in tempering and heating a substrate for shape-changing.When both the metal and the metal oxymaterial films are used either maybe deposited first for the protective layer with the other film over thefirst deposited film for layer H. Generally the thickness of the filmsare for the metal film about 5 to about 60 Angstroms (Å), preferablyabout 10 to about 30 Å and most preferably 15 to 25 Å. The metal oxyfilm can have a thickness in the range from about 20 to about 50 Å,preferably 30 to 40 Å. Further, more than one protective film may beused. For example, but not limiting to the invention, a zinc oxide filmover a titanium dioxide film may be used. The thickness of the Layer His not limiting to the invention; however, the thickness should be thickenough to provide protection. The metal, metal oxy films can bedeposited by any method known to those skilled in the art. Also part ofthe metal film can be oxidized by heating rather than depositing aseparate metal oxide film.

Before discussing in detail the Samples of the Table 1, the followingbackground information is provided for a better appreciate of theinvention.

Using zinc oxide film, as discussed above, provides a silver layerhaving resistivity and emissivity lower than a silver layer deposited ona zinc stannate layer having less than about 60 weight percent zinc andmore than about 40 weight percent tin.

U.S.P.N. '001 discusses increasing the thickness of the primer layer toenhance the mechanical durability of the coated article to make thecoated article shippable. More particularly, U.S.P.N. 001 discloses thatit has been found that where the coated article will be exposed to heattreatment during its production, there is a point at which the primerlayer may be made either too thin or too thick. Too thin a primer layerresults in a lack of protection for the reflective, metallic film fromoxidation at high temperature thus rendering the coated articleunacceptable for heat treatment and in poor shear resistance which makesthe article unsuitable for long distance shipment for later thermalprocessing. Too thick a primer layer results in the formation of anundesirable haze in the coated article after heat treatment, alsorendering it unacceptable for heat treatment. However, a limitation isthat these films after heating have haze.

It has been determined that by selecting dielectric films and primerlayers that a coating stack can be made that has reduced haze afterheating. For coated articles that are shipped but not heated, the primerlayer should be thick enough to protect the silver during deposition ofthe overlying dielectric film or layer on the silver layer. A thicknessof primer layers in the range of about 8 to 12 Angstroms is sufficient.The thickness of the primer layer is increased when the primer layer isto protect the silver during heating of the coated article. A thicknessof about 20±5 Å is acceptable.

For a coated article that is shippable and heatable with reduced haze,the thickness of the primer film is adjusted to compliment thedielectric layer or film arrangement. In accordance with the teachingsof the invention, primer layer thickness in the range of 18-32 Angstroms(Å) and preferably 18-40 Å is acceptable to provide a coating stack withreduced haze after heating. The following Examples illustrate theinvention.

In the following discussion, the thickness of the metal primer layer isas deposited. As can be appreciated, the thickness increases afterheating, changing a portion of the titanium metal primer film totitanium oxide. A method that will be referred to as the “XRF Method” isdiscussed in U.S.P.N. '001. In general the XRF Method is used to measurethe thickness of metal layers. The XRF Method uses calibrated x-rayfluorescence instrument to measure the weight of the metal per unit areaof the coating (namely, in μg/cm²). The XRF Method makes the assumptionthat the metal film is as dense as its bulk form. With this assumption,the metal film's measured weight per unit area is then converted to athickness in Angstroms, using its bulk density. For completeness sake,it should be noted that sputtered metal films are often less dense thantheir corresponding bulk metals, so that above described assumption isnot always precisely correct, and the XRF Method may in some casesunderestimate the thickness of the metal film due to this variation indensity. Thus, for the thin metal films, the initial measurement ofweight per unit area (μg/cm²) is more accurate than the correspondingconversion to thickness based upon bulk density. Nonetheless, the XRFMethod provides a useful approximation for comparing the relativethicknesses of the layers in coating.

In the following discussion, the thickness of the dielectric layersand/or films are given in ranges. As can be appreciated by those skilledin the art, the ranges are not limiting to the invention and thethickness may be selected to provide a coating stack of a desired color.

EXAMPLE 1

This Example 1 is Sample 1 of the Table 1. Sample 1 is a coated articlethat is shippable and heatable. The coating is a high transmittance, lowemissivity coated article having a single infrared, reflective layer.Product having the coating stack of Sample 1 is made and the coatingstack includes:

a clear glass substrate; a dielectric, antireflective layer deposited onthe substrate, the layer includes (1) a zinc stannate film having 52weight percent zinc and 48 weight percent tin (hereinafter referred toas 52-48 zinc stannate film) and having a thickness of 260±40 Å, and (2)a zinc stannate film having 90 weight percent zinc and 10 weight percenttin (hereinafter referred to as 90-10 zinc stannate film) and having athickness of about 80±45 Å;

a silver film having a thickness of about 115±15 Å deposited on the90-10 zinc stannate film,

a titanium primer film having a thickness of 24-28 Å deposited on themet all ic reflective film;

a dielectric, antireflective upper layer deposited on the titaniumprimer film, the dielectric, antireflective upper film includes a 52-48zinc stannate film having a thickness of about 230±60 Å deposited on theprimer layer metal oxide, and

a titanium oxide layer having a thickness of 36±7 Å deposited on the52-48 zinc stannate layer or film.

EXAMPLE 2

This Example 2 is Sample 2 of the Table 1. The coated article has bee nmade and is shippable and heatable with reduced haze. The coated articleincludes a glass substrate/a layer of a 52-48 zinc stannate film havinga thickness of about 230±20 Å and a zinc oxide film having a thicknessof about 80±40 Å; a silver film having a thickness of 110±10 Å; atitanium metal primer film having a thickness of about 18-23 Å andpreferably 19.5 Å; a 52-48 zinc stannate film having a thickness ofabout 820±40 Å; a silver film having a thickness of about 110±10Å; ametal primer having a thickness of about 18-31 Å and preferably 25 Å; a52-48 zinc stannate film having a thickness of about 200±20 Å, and atitanium film having a thickness of about 29±3 Å.

EXAMPLE 3

This Example 3 is Sample 3 of the Table 1. The coated article was notmade; however, the following coated article is expected to be shippableand heatable with reduced haze. Example 3 includes a clear glasssubstrate; a dielectric, antireflective base layer deposited on thesubstrate includes a 52-48 zinc stannate film having a thickness ofabout 310±20 Å deposited on the glass substrate; a first silver filmhaving a thickness of about 110±10 Å deposited on the 52-48 zincstannate film; a first titanium primer film having a thickness of 18-29Å deposited on the first silver film; a dielectric, antireflectiveintermediate layer deposited on the first primer film, the intermediatelayer includes a zinc oxide film having a thickness of 80±40 Å depositedon the first primer film, a 52-48 zinc stannate film having a thicknessof 740±40 Å deposited on the zinc oxide film; a second silver filmhaving a thickness of about 110±10 Å deposited on the 52-48 zincstannate film of the intermediate layer; a second titanium primer filmhaving a thickness of about 18-31 Å deposited on the second silver film;a dielectric, antireflective upper layer deposited on the second primerfilm, the dielectric upper layer is a 52-48 zinc stannate film having athickness of about 200±20 Å; and a titanium metal protective film havinga thickness of about 29±3 Å, deposited on the 52-48 zinc stannate filmof the dielectric upper layer.

EXAMPLE 4

This Example 4 is Sample 4 of the Table 1. The coated article of Example4 was made and is shippable and heatable with the heated, coated articlehaving reduced haze. The coated article of this Example 4 includes aclear glass substrate; a 52-48 zinc stannate film having a thickness of310±20 Å deposited on the glass substrate; a first silver film having athickness of 110±10 Å deposited on the 52-48 zinc stannate film; a firsttitanium primer having a thickness of 18-29 Å and preferably 22.5 Ådeposited on the first silver film; a 52-48 zinc stannate film having athickness of about 820±40 Å deposited on the first titanium film; asecond silver film having a thickness of about 110±10 Å deposited on the52-48 zinc stannate film; a second titanium film having a thickness of18-32 Å and preferably 21.5 Å is deposited on the second silver layer; azinc oxide film having a thickness of 80±40 Å deposited on the secondtitanium primer layer; a 52-48 zinc stannate film having a thickness of120±40 Å deposited on the zinc oxide film and a titanium overcoat filmhaving a thickness of 29±3 Å over the 52-48 zinc stannate film.

EXAMPLE 5

This Example 5 is Sample 5 of the Table 1. The coated article was notmade; however, it is expected that the coated article is suitable forshipment and heat treatment with the heated, coated article havingreduced haze. The coated article of this Example 5 includes the filmsand layers similar to Example 3 except Sample 5 has a 52-48 zincstannate film having a thickness of about 230±40 Å deposited on thesubstrate and a zinc oxide film having a thickness of about 80±40 Ådeposited on the 52-48 zinc stannate film. The first titanium primerfilm on the first silver layer has a thickness of about 18-29 Å; thesecond titanium primer film on the second silver layer has a thicknessof about 18-31 Å. The remaining layers of Sample 5 are as shown in theTable and have the same composition and thickness for the same films asdescribed in Example 3.

EXAMPLE 6

This Example 6 is Sample 6 of the Table 1 and was made and is shippableand heatable with the heated, coated article having reduced haze. Thecoated stack is similar to the coating stack of Example 2 except a zincoxide film having a thickness of about 80±40 Å is deposited on thesecond titanium primer and a 52-48 zinc stannate film having a thicknessof 120±40 Å is deposited on the zinc oxide film. The first titaniumprimer layer had a thickness of 19-26 Å and preferably 19.5 Å, and thesecond primer layer had a thickness of 21.5-31 Å and preferably 25 Å.The composition and thickness of the remaining films/layers for Example6 as shown for Sample 6 in the Table are as described in Example 2.

EXAMPLE 7

This Example 7 is Sample 7 of the Table 1 and was made and is shippableand heatable with the heated coating stack having reduced haze. Thecoating stack of Sample 7 is similar to the coating stack of Example 3except a zinc oxide film having a thickness of about 80±40 Å wasdeposited on the second titanium film and a 52-48 zinc stannate film wasdeposited on the zinc oxide film. The first titanium primer layer had athickness of about 22-26 Å and preferably 22.5 Å, and the secondtitanium primer layer had a thickness of about 18-25 Å and preferably21.5 Å. The composition and thickness of the remaining films/layers forExample 7 as shown for Sample 7 on the Table are as described in Example2.

EXAMPLE 8

This Example 8 is Sample 8 of the Table. The coated article was made andis a coated article suitable for shipment and heat treatment with theheated coated articles having reduce haze. The coated article of thisExample 8 is a coated stack deposited on a clear glass substrate. Thecoating thickness and order of the films is as follows with film 1deposited on the glass substrate.

TABLE 2 Film No. from Table Composition of the Film Thickness of theFilm 1 52-48 zinc stannate 230 ± 40Å 2 zinc oxide  80 ± 40Å 3 1^(st)silver 110 ± 30Å 4 1^(st) titanium primer  17-26Å, preferably 19.5Å 5zinc oxide  80 ± 40Å 6 52-48 zinc stannate 740 ± 40Å 8 2^(nd) silverfilm 110 ± 30Å 9 2^(nd) titanium primer  18-31Å, preferably 28Å 10 zincoxide  80 ± 40Å 11 52-48 zinc stannate 120 ± 40Å 12 titanium metalovercoat  29 ± 3Å

The coated glass having the above coating was used in the fabrication ofautomotive windshields. The coated glass was cut to size, heated toshape the coated glass, and thereafter laminated to another shaped glassto provide an automotive windshield. The transmittance of the laminatewas greater than 70%, and reflects infrared energy. The windshield wasmade as is known in the art. Coated glass for use in automotivewindshield was also made substituting 90-10 zinc stannate for the zincoxide film. The coated article had film thickness in the ranges recitedon Table 2.

As can be appreciated, the thickness of the primer layers presented inTable 2 can vary depending on cathode and sputtering equipment. Forexample, a shippable and heatable coating stack with reduced haze wasmade with a first titanium primer film having a thickness of 18±0.5 Åand the second titanium primer film having a thickness of 22±1 Å

EXAMPLE 9

This Example 9 is Sample 9 of the Table and is a coated article that wasmade. The coated article was shippable and heatable with the heated,coated article having reduced haze. The coated article of this Example 9is a coated stack deposited on a clear glass substrate. The coatingthickness and order of the films is as follows with film 1 deposited onthe glass substrate.

TABLE 3 Film No. from Table Composition of the Film Thickness of theFilm 1 52-48 zinc stannate 230 ± 40Å 2 90-10 zinc stannate  80 ± 40Å 31^(st) silver 107 ± 30Å 4 1^(st) titanium primer  17-24Å, preferably21.5Å 5 90-10 zinc stannate  80 ± 40Å 6 52-48 zinc stannate 600 ± 100Å 790-10 zince stannate  80 ± 30Å 8 2^(nd) silver 127 ± 30Å 9 titaniummetal primer  20-26Å, preferably 22.5Å 10 90-10 zinc stannate  80 ± 40Å11 52-48 zinc stannate 160 ± 60Å 12 titanium oxide overcoat  45 ± 15Å

As can now be appreciated, a 90-10 zinc stannate film, a zinc oxide filmand a zinc oxide, tin oxide film may be interchanged with one anotherand substituted for one another to obtain coated articles that areshippable and heatable with reduced haze. However, in the practice ofthe invention the 9-10 zinc stannate film is preferred.

EXAMPLES 10-11

Examples 10 and 11 are Samples 10 and 11 of the Table. These exampleswere similar to example 9 with the following exceptions. For Example 10titanium metal was the overcoat and for Example 11 titanium metal andtitanium oxide were the overcoats. Example 11 was conducted in analternative manner were the protective layer was first the titaniumoxide film with the titanium film over top of it.

As can be appreciated, the thickness of the films is not limiting to theinvention and may be selected to provide a coated article of a desiredcolor as is known in the art. Further, the films of all examples of theinvention may be interchanged to attain the features of the invention. Acomplete discussion of heating the coated glass sheets to automotivewindshields, residential and commercial windows and other transparencieswas not given as such technology is known in the art and as can now beappreciated used in the practice of the invention.

The invention is not limited to the examples presented above and thatvarious changes and alterations can be made without departing from thespirit and broader aspects of the invention, as defined by the claimsset forth below and by the range of equivalency allowed by law.

What is claimed is:
 1. An infrared reflective coated article comprising:a substrate; a dielectric layer sputter deposited over the substrate,the layer comprising a first zinc stannate film deposited over thesubstrate having zinc in weight percent range of equal to and greaterthan 10 and equal to and less than 90, and tin in the weight percentrange of equal to and less than 90 and equal to and greater than 10, andan electrical enhancing film deposited over the zinc stannate film, theelectrical enhancing film selected from the group of films consisting ofzinc oxide, tin oxide film and a second zinc stannate film wherein thecomposition of the first zinc stannate film is at least about 5 weightpercent different than the composition of the second zinc stannate film,and an infrared reflective layer deposited on the dielectric layer, ametal primer layer over the infrared reflective layer; a seconddielectric layer over the primer layer; and a protective layer of atleast two films selected from the group consisting of metal-containingfilms which are from different transition metals of Groups 4, 5, 6, or10 of the Periodic Table of Elements, silicon-containing films, metaland silicon films, films of metal and metal-oxy materials, films ofmetal and silicon oxy-materials, films of silicon and metal-oxymaterials, films of silicon and silicon oxy-materials, and films ofmetal oxy and silicon oxy materials, where the oxy materials areselected from the group consisting of oxides and oxynitrides, andwherein the protective layer is in a position where it can perform theprotective function for providing durability to the dielectric layer,infrared reflective layer, metal primer layer, and second dielectriclayer.
 2. The coated article of claim 1 wherein the infrared reflectivemetal is silver and the silver is deposited on the zinc oxide, tin oxidefilm.
 3. The coated article of claim 1 wherein the infrared reflectivelayer is a silver film and the silver film is deposited on the secondzinc stannate film.
 4. The coated article of claim 1 wherein thedielectric layer is a first dielectric layer, the infrared reflectivelayer is a first infrared reflective layer, the metal primer layer isover the first infrared reflective layer, and the protective layer is anovercoat over the second dielectric layer.
 5. The coated article ofclaim 4 wherein the second dielectric layer is a zinc stannate filmhaving 10-90 weight percent zinc and 90-10 weight percent tin.
 6. Thecoated article of claim 1 wherein the dielectric layer is a firstdielectric layer and the infrared reflective layer is a first infraredreflective layer and further including: a first metal primer layer overthe first infrared reflective metal layer; a second dielectric layerover the first primer layer; a second infrared reflective layer over thesecond dielectric layer; a second metal primer layer over the secondinfrared reflective layer; a third dielectric layer over the secondmetal primer layer; and the protective layer is over the thirddielectric layer.
 7. The coated article of claim 6 wherein at least oneof the second and third dielectric layers includes a zinc stannate filmhaving 10-90 weight percent zinc and 90-10 weight percent tin.
 8. Thecoated article of claim 1 wherein the dielectric layer is a firstdielectric layer and the infrared reflective layer is a first infraredreflective layer and further including: a first metal primer layer overthe first reflective layer; a second dielectric layer over the firstmetal primer layer, the second dielectric layer comprising a firstdielectric film and a zinc stannate film defined as a first zincstannate film, the first zinc stannate film having zinc in the weightpercent range of equal to and greater than 10 and equal to and less than90 and tin in the weight percent range of equal to and greater than 10and equal to and less than 90, the second dielectric layer depositedover the first metal primer layer; a second infrared reflective layerdeposited over the second dielectric layer; a second metal primer layerdeposited over the second infrared reflective layer; a third dielectriclayer deposited over the second primer layer; and the protective layeris over the third dielectric layer.
 9. The coated article of claim 8wherein the first dielectric film of the second dielectric layer isselected from the group consisting of a zinc oxide film, a zinc oxide,tin oxide film, and a zinc stannate film defined as a second zincstannate film, the second zinc stannate film having a compositiondifferent than the composition of the first zinc stannate film of thesecond dielectric layer.
 10. The coated article of claim 9 wherein thesecond zinc stannate film of the second dielectric layer has zinc in theweight percent range of equal to and greater than 60 and equal to andless than 90 and tin in the weight percent of equal to and greater than10 and equal to and less than 40, and the third dielectric layer is azinc stannate film.
 11. The coated article of claim 1 wherein thedielectric layer is a first dielectric layer and the infrared reflectivelayer is a first infrared reflective layer and further including: afirst metal primer layer over the first reflective layer; a seconddielectric layer over the first metal primer film; a second infraredreflective layer over the second dielectric layer; a second metal primerlayer over the second infrared reflecting metal layer; a thirddielectric layer over the second metal primer layer, the thirddielectric layer comprising a first dielectric film and a zinc stannatefilm defined as a first zinc stannate film, the first zinc stannate filmhaving zinc in a weight percent with the range of equal to and greaterthan 10 and equal to and less than 90 and tin within the weight percentrange of equal to and less than 90 and equal to and greater than 10, thethird dielectric film deposited over the second metal primer; and theprotective layer overlies the third dielectric film.
 12. The coatedarticle of claim 11 wherein the first dielectric film of the thirddielectric layer is selected from the group consisting of a zinc oxidefilm, a zinc oxide, tin oxide film, and a zinc stannate film defined asa second zinc stannate film, the second zinc stannate film having acomposition different than the composition of the first zinc stannatefilm of third dielectric layer.
 13. The coated article of claim 12wherein the second zinc stannate film of the third dielectric layer haszinc in the weight percent range of equal to and greater than 60 andequal to and less than 90 and tin in the weight percent range of equalto and greater than 10 and equal to and less than
 40. 14. The coatedarticle of claim 1 wherein the dielectric layer is a first dielectriclayer, the infrared reflective layer is a first infrared reflectivelayer, the metal primer layer is a first metal primer layer over thefirst reflective layer, and the second dielectric layer is over thefirst metal primer layer, the second dielectric layer comprising a firstdielectric film and a zinc stannate film defined as a first zincstannate film, the first zinc stannate film having zinc in a weightpercent within the range of equal to and greater than 10 and equal toand less than 90 and tin within the weight percent range of equal to andless than 90 and equal to and greater than 100, the second dielectriclayer deposited over the first metal primer layer, and furthercomprising; a second infrared reflective layer over the first zincstannate film of the second dielectric layer; a second metal primerlayer over the second infrared reflective layer; a third dielectriclayer over the second metal primer layer, the third dielectric layercomprising a first dielectric film and a zinc stannate film defined as afirst zinc stannate film, the first zinc stannate film having zinc in aweight percent within the range of equal to and greater than 10 andequal to and less than 90 and tin within the weight percent range ofequal to and less than 90 and equal to and greater than 10, the thirddielectric layer deposited over the second metal primer layer; and theprotective layer overlies the first zinc stannate film of the thirddielectric layer.
 15. The coated article of claim 14 wherein the firstdielectric film of the second dielectric layer and the first dielectricfilm of the third dielectric layer each has a film selected from thegroup consisting of a zinc oxide film, a zinc oxide, tin oxide film, anda second zinc stannate film having a composition different than thecomposition of the first zinc stannate film in their respective secondor third dielectric layer.
 16. The coated article of claim 15 whereinthe second zinc stannate film of the first and second dielectric layereach include zinc in the weight percent range of equal to and greaterthan 60 and equal to and less than 90 and tin in the weight percent ofequal to and greater than 10 and equal to and less than
 40. 17. Thecoated article of claim 15 wherein the second dielectric layer furtherincludes a third dielectric film over the first zinc stannate film ofthe second dielectric layer wherein the third dielectric film of thesecond dielectric layer is a film selected from the group consisting ofa zinc oxide film, a zinc oxide, tin oxide film and a zinc stannate filmdefined as a third zinc stannate film, the third zinc stannate film hasa composition different than the composition of the first zinc stannatefilm of the second dielectric layer closest to the third zinc stannatefilm.
 18. The coated article of claim 15 wherein the second dielectriclayer further includes a third dielectric film over the first zincstannate film of the second dielectric layer, wherein the thirddielectric film of the second dielectric layer is selected from thegroup consisting of a zinc oxide film, a zinc oxide, tin oxide film, anda second zinc stannate film defined as a third zinc stannate film, thethird zinc stannate film of the second dielectric layer having acomposition different than the composition of the first zinc stannatefilm of second dielectric layer.
 19. The coated article of claim 18wherein the first and third dielectric films of the second dielectriclayer and the first dielectric film of the third dielectric layer eachinclude zinc in the weight percent range of equal to and greater than 60and equal to and less than 90 and tin in the weight percent of equal toand greater than 10 and equal to and less than
 40. 20. The coatedarticle of claim 15 wherein the third dielectric layer further includesa third dielectric film over the first zinc stannate film of the thirddielectric layer, wherein the third dielectric film of the thirddielectric layer is selected from the group consisting of a zinc oxidefilm, a zinc oxide, tin oxide film, and a zinc stannate film defined asa third zinc stannate film, the third zinc stannate film of the thirddielectric layer having a composition different than the composition ofthe first zinc stannate film of third dielectric layer.
 21. The coatedarticle of claim 14 wherein the second dielectric layer further includesa third dielectric film over the first zinc stannate film of the seconddielectric layer.
 22. The coated article of claim 14 wherein thesubstrate is a glass piece and the first zinc stannate film of the firstdielectric layer is on the glass piece and has a thickness in the rangeof 230±40 Angstroms Å; the electrical enhancing film of the firstdielectric layer is on the first zinc stannate film of the firstdielectric layer and has a thickness in the range of 80±40 Å; the firstinfrared reflective metal layer is a first silver film deposited on theelectrical enhancing film of the first dielectric layer and has athickness in the range of 110±30 Å, the metal primer layer is a titaniumfilm deposited on the first silver layer and has a thickness in therange of 17-26 Å; the first dielectric film of the second dielectriclayer is deposited on the titanium film and has a thickness in the rangeof 80±40 Å; the first zinc stannate film of the second dielectric layeris deposited on the first dielectric film of the second dielectric layerand has a thickness in the range of 740±40 Å; the second infraredreflective metal layer is a second silver film deposited on the firstzinc stannate film of the second dielectric layer and has a thickness inthe range of 110±38 Å; the second primer film is a titanium filmdeposited on the second silver layer and having a thickness in the rangeof 18-31 Å; the first dielectric film of the third dielectric layer isdeposited on the second titanium film and has a thickness in the rangeof 80±40 Å; the first zinc stannate film layer of the third dielectriclayer is deposited on the first dielectric film of the third dielectriclayer and has a thickness in the range of 120±40 Å, and the protectivelayer includes a titanium metal film deposited on the first zincstannate film layer of the third dielectric layer and has a thickness inthe range of 29±3 Å.
 23. The coated article of claim 22 wherein theprotective coating further includes a titanium oxide film.
 24. Thecoated article of claim 1 wherein the protective layer has at least twofilms selected from the group consisting of a metal of titanium,zirconium, niobium, tantalum, chromium, nickel or alloys thereof, ametal oxy material of titanium oxides, titanium oxynitride, zirconiumoxides, zirconium oxynitrides, niobium oxides, niobium oxynitrides,tantalum oxide, tantalum oxynitride, chromic oxides, chromicoxynitrides, nickel oxide, nickel oxynitride, silicon oxide, silicondioxide, and silicon aluminum nitride, and combinations and mixtures ofany two or more of these.
 25. The coated article of claim 1, wherein theprotective layer has a thickness of about 5 to about 60 Å for the metalor silicon films and about 20 to about 50 Å for the metal oxy-materialor silicon oxy-material films.
 26. The coated article of claim 25,wherein the protective layer has a thickness of 10 to about 30 Å for themetal or silicon films and 30 to 40 Å for the metal oxy-material orsilicon oxy-material films.
 27. The coated article of claim 1, whereinthe protective layer provides chemical durability.
 28. The coatedarticle of claim 1, wherein the protective layer provides mechanicaldurability.
 29. A coated article comprising: a substrate; a firstdielectric layer over the substrate; a first infrared reflective layerover the first dielectric layer; a first metal primer layer over thefirst infrared reflective layer; a second dielectric layer over thefirst metal primer, the second dielectric layer having a firstdielectric film selected from the group consisting of a zinc oxide, tinoxide film and a first zinc stannate film, and a second dielectric filmhaving a composition different than the first dielectric film of thesecond dielectric layer; a second infrared reflective layer over thesecond dielectric layer; a second primer layer over the secondreflective layer; a third dielectric layer over the second metal primerlayer; and a protective layer of at least two films selected from thegroup consisting of metal-containing films, which are selected fromdifferent transition metals of Groups 4, 5, 6 or 10 of the PeriodicTable of Elements, silicon-containing films, metal and silicon films,films of metal and metal-oxy materials, films of metal and siliconoxy-materials, films of silicon and metal-oxy materials, films ofsilicon and silicon oxy-materials, and films of metal oxy and siliconoxy materials, where the oxy-materials are oxides or oxynitrides andwherein the protective layer is in a position where it can perform theprotective function for providing durability to the dielectric layers,infrared reflective layers, and metal primer layers.
 30. The coatedarticle of claim 29 wherein the first dielectric layer includes a zincstannate film, the second dielectric film of the second dielectric layeris a zinc stannate film and the third dielectric layer includes a zincstannate film, each of the zinc stannate films having zinc in the weightpercent range of 10-90 and tin in the weight percent range of 90-10. 31.The coated article of claim 30 wherein the first dielectric film of thesecond dielectric layer is the first zinc stannate film having zinc inthe weight percent range of equal to and greater than 90 and equal toand less than 60 and tin in the weight percent range of equal to andgreater than 10 and equal to and less than
 40. 32. A coated articlecomprising: a substrate; a first dielectric layer over the substrate; afirst infrared reflective layer over the first dielectric layer; a firstmetal primer layer over the first infrared reflective layer; a seconddielectric layer over the first metal primer layer; a second infraredreflective layer over the second dielectric layer; a second metal primerlayer over the second reflective metal layer; a third dielectric layerhaving a first dielectric film selected from the group consisting of azinc oxide film, a zinc oxide, tin oxide film, and a zinc stannate film,and a second dielectric film overlying the first dielectric film, thesecond dielectric film having a composition different from the firstdielectric film; and the protective layer overlying the third dielectriclayer where the protective layer is at least two films selected from thegroup consisting of: metal-containing films, which are of differenttransition metals of Groups 4, 5, 6 or 10 of the Periodic Table ofElements, silicon-containing films, metal and silicon films, films ofmetal and metal-oxy materials, films of metal and silicon oxy-materials,films of silicon and metal-oxy materials, films of silicon and siliconoxy-materials, and films of metal oxy and silicon oxy materials, wherethe oxy-materials are selected from the group of oxides or oxynitrides.33. The coated article of claim 32 wherein the first and seconddielectric layers are each a zinc stannate film, and the seconddielectric film of the third dielectric layer is a zinc stannate filmand each of the zinc stannate films has zinc in the weight percent rangeof 10-90 and tin in the weight percent range of 90-10.
 34. The coatedarticle of claim 33 wherein the first dielectric film of the thirddielectric layer has zinc in the weight percent range of equal to andgreater than 90 and equal to and less than 60 and tin in the weightpercent range of equal to and greater than 10 and equal to and less than40.
 35. A coated article comprising: a substrate; a first dielectriclayer over the substrate; a first infrared reflective layer over thefirst dielectric layer; a first primer layer over the first reflectivemetal layer; a second dielectric layer having a first dielectric filmselected from the group consisting of a zinc oxide, tin oxide film and afirst zinc stannate film, and a second dielectric film overlying thefirst dielectric film having a composition different than the firstdielectric film of the second dielectric layer; a second infraredreflective layer over the second dielectric layer; a second primer layerover the second reflective layer; a third dielectric layer over thesecond metal primer layer, the third dielectric layer having a firstdielectric film selected from the group consisting of a zinc oxide, tinoxide film and zinc stannate film, and a second dielectric film, thesecond dielectric film of the third dielectric layer having acomposition different than the composition of the first dielectric filmof the third dielectric layer; and the protective layer overlying thethird dielectric layer where the protective layer is at least two filmsselected from the group consisting of: metal-containing andsilicon-containing films, which are different metals, or metal andsilicon, or metal and metal-oxy materials, or metal and siliconoxy-materials, or silicon and metal-oxy, or silicon and siliconoxy-materials, or metal oxy and silicon oxy materials, where the oxymaterials are selected from the group consisting of oxides andoxynitrides and where the metal is selected from the group consisting ofa transition metal of Groups 4, 5, 6 or 10 of the Periodic Table ofElements.
 36. The coated article of claim 35 wherein the firstdielectric layer, the second dielectric film of the second and thirddielectric layers are each a zinc stannate film having zinc in theweight percent range of 10-90 and tin in the weight percent range of90-10.
 37. The coated article of claim 36 wherein the first dielectricfilm of the second and third dielectric layers are each a zinc stannatefilm having zinc in the weight percent range of equal to and greaterthan 90 and equal to and less than 60 and tin in the weight percentrange of equal to and greater than 10 and equal to and less than
 40. 38.The coated article of claim 36 wherein the coated article is atransparency.
 39. The coated article of claim 38 wherein the coatedarticle is an automotive transparency.
 40. The coated article of claim39 wherein the automobile transparency is an automotive windshieldhaving a pair of glass sheets laminated together and one of the sheetsis fabricated from the substrate having the coating.
 41. An infraredreflective coated article comprising: a glass substrate; a firstdielectric layer over the substrate, the first dielectric layercomprising a dielectric film over a zinc stannate film, wherein the zincstannate film of the first dielectric layer has a thickness in the rangeof 230±40 Angstroms Å and has zinc in weight percent range of equal toand greater than 10 and equal to and less than 90 and tin in the weightpercent range of equal to and less than 90 and equal to and greater than10, and the dielectric film of the first dielectric layer has athickness in the range of 80±40 Å and is different from the zincstannate film of the first dielectric layer; a first infrared reflectivelayer over the first dielectric layer, wherein the first infraredreflective metal layer is a first silver film and has a thickness in therange of 110±30 Å; a first metal primer layer over the first infraredreflective layer, wherein the metal primer layer is a titanium film andhas a thickness in the range of 17-26 Å; a second dielectric layer overthe first metal primer layer, the second dielectric layer comprising azinc stannate film over a dielectric film, wherein the dielectric filmof the second dielectric layer has a thickness in the range of 80±40 Å,the zinc stannate film of the second dielectric layer has a thickness inthe range of 740±40 Å and has zinc in a weight percent within the rangeof equal to and greater than 10 and equal to and less than 90 and tinwithin the weight percent range of equal to and less than 90 and equalto and greater than 10, and the dielectric film of the second dielectriclayer is different from the zinc stannate film of the second dielectriclayer; a second infrared reflective layer over the second dielectriclayer, wherein the second infrared reflective metal layer is a secondsilver film and has a thickness in the range of 110±38 Å; a second metalprimer layer over the second infrared reflective layer, wherein thesecond primer film is a titanium film and has a thickness in the rangeof 18-31 Å; a third dielectric layer over the second metal primer layer,the third dielectric layer comprising a zinc stannate film over adielectric film, wherein the dielectric layer of the third dielectriclayer has a thickness in the range of 80±40 Å, the zinc stannate film ofthe third dielectric layer has a thickness in the range of 120±40 Å andhas zinc in a weight percent within the range of equal to and greaterthan 10 and equal to and less than 90 and fin within the weight percentrange of equal to and less than 90 and equal to and greater than 10, andthe dielectric film of the third dielectric layer is different from thezinc stannate film of the third dielectric layer; and a protective layerof titanium metal film over the third dielectric layer and having athickness in the range of 29±3 Å.